Evaluation of radiation sensitivity and mating performance of Glossina brevipalpis males

Abstract

BackgroundArea-wide integrated pest management strategies that include a sterile insect technique component have been successfully used to eradicate tsetse fly populations in the past. To ensure the success of the sterile insect technique, the released males must be adequately sterile and be able to compete with their native counterparts in the wild.Methodology/Principal findingsIn the present study the radiation sensitivity of colonised Glossina brevipalpis Newstead (Diptera; Glossinidae) males, treated either as adults or pupae, was assessed. The mating performance of the irradiated G. brevipalpis males was assessed in walk-in field cages. Glossina brevipalpis adults and pupae were highly sensitive to irradiation, and a dose of 40 Gy and 80 Gy induced 93% and 99% sterility respectively in untreated females that mated with males irradiated as adults. When 37 to 41 day old pupae were exposed to a dose of 40 Gy, more than 97% sterility was induced in untreated females that mated with males derived from irradiated pupae. Males treated as adults with a dose up to 80 Gy were able to compete successfully with untreated fertile males for untreated females in walk-in field cages.Conclusions/SignificanceThe data emanating from this field cage study indicates that, sterile male flies derived from the colony of G. brevipalpis maintained at the Agricultural Research Council-Onderstepoort Veterinary Institute in South Africa are potential good candidates for a campaign that includes a sterile insect technique component. This would need to be confirmed by open field studies.

Gamma Irradiation and Male Glossina austeni Mating Performance

“…High insemination rates (91.9-100%) were observed irrespective whether the males were irradiated as adults or pupae. This study further showed that males irradiated as adults with 80 Gy successfully competed with colonized fertile males for colony females under semi-field conditions [25], indicating that the G. brevipalpis colony at the Agricultural Research Council-Onderstepoort Veterinary Institute (ARC-OVI) can provide sterile males suitable for a release program [25].…”

“…A zip, also in a black nylon strip, from top to bottom sealed the entrance of the cage. The field cages were deployed in a small irrigated forest, at the ARC-OVI in Pretoria South Africa, as described previously [25]. The field cage experiments were carried out in the afternoon from 12:00 to 15:00.…”

“…There are positive and negative considerations when deciding to irradiate adult flies or pupae [25]. Adult pupae are easier to transport, more robust to handle and larger volumes of pupae can be irradiated simultaneously [19].…”

“…Releasing low quality sterile males will necessitate higher release rates, require more funding that might prolong the duration of the program and potential failure [52]. A recent study indicated that treating late stage G. brevipalpis pupae with 40 Gy induced 97% sterility when mated with untreated females and 99% sterility when irradiated with 80 Gy as adults [25]. High insemination rates (91.9-100%) were observed irrespective whether the males were irradiated as adults or pupae.…”

Enhancing vector refractoriness to trypanosome infection: achievements, challenges and perspectives

“…The recovery of Sodalis titers in sterile males opens the door to combine paratransgenesis with SIT for tsetse control. In addition, pupal irradiation is operationally advantageous in terms of handling and transportation compared to adult irradiation [ 96 ].…”